20947 has 2 divisors, whose sum is σ = 20948. Its totient is φ = 20946.

The previous prime is 20939. The next prime is 20959. The reversal of 20947 is 74902.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20947 - 2³ = 20939 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20047) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10473 + 10474.

It is an arithmetic number, because the mean of its divisors is an integer number (10474).

2²⁰⁹⁴⁷ is an apocalyptic number.

20947 is a deficient number, since it is larger than the sum of its proper divisors (1).

20947 is an equidigital number, since it uses as much as digits as its factorization.

20947 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 504, while the sum is 22.

The square root of 20947 is about 144.7307845622. The cubic root of 20947 is about 27.5660122135.

It can be divided in two parts, 209 and 47, that added together give a 8-th power (256 = 2⁸).

The spelling of 20947 in words is "twenty thousand, nine hundred forty-seven".